A363203 Number of free linear polycubes of size n, identifying rotations and reflections and avoiding neighbors at [0,0,+-2], [0,+-2,0], and [+-2,0,0].

1, 1, 1, 2, 4, 9, 20, 51, 128, 338, 882, 2350, 6238, 16693, 44561, 119339, 319104, 854420, 2285357

Offset: 1

Author

Joerg Arndt and Márk Péter Légrádi, May 21 2023

Keywords

• nonn
• more

Comments

Linear polycubes have two end points with one neighbor, the remaining cubes all have two neighbors.

When a cube [x,y,z] is in the polycube then neither of the six cubes [x+-2,y,z], [x,y+-2,z], [x,y,z+-2] can be in the polycube. For example, no three cubes can be in a row.

Crossrefs

Cf. A363204 (linear and avoiding at [+-1,+-1,+-1]).